Field of the Invention
The present invention relates to information processing of measuring three-dimensional positions on the surface of an object from an image obtained by capturing the object on which a geometric pattern has been projected, and a measurement apparatus.
Description of the Related Art
As one of three-dimensional position measurement methods, there is known a method called an “active stereo method” of projecting a geometric pattern on an object to be measured, and measuring three-dimensional positions on the surface of the object based on information of an image obtained by capturing the object. At the time of measurement by the active stereo method, the size and shape of a projection image on the image vary due to the influence of a blur and motion blur or the influence of the position and angle of the object surface. Therefore, it becomes difficult to decide the position of the projection image on the image at high accuracy.
To cope with this problem, according to Japanese Patent Laid-Open No. 2011-204280 (literature 1), it is possible to decide the position of a projection image according to a variation of the size of the projection image on an image by preparing images of a plurality of resolutions and checking a filter response to the image of each resolution.
However, the method described in literature 1 decides the position of the projection image based on the images of the plurality of resolutions but does not set an image resolution according to the size of the projection image observed on the image. Thus, the position decision accuracy is low. Consequently, even if the method described in literature 1 is applied to three-dimensional position measurement, the position measurement accuracy is insufficient.